The current invention is an appliance for the irradiation of internal cavities of the body, in particular for the treatment of specific diseases using photodynamic therapy. This appliance is comprised of a flexible catheter, made of transparent material containing a fiber optic with the section at its tip being used to radially diffuse light from a source at the other end of this fiber, and an inflatable small balloon in elastomeric material which diffuses the light and which is fixed to the extremity of the catheter and surrounds the diffusing section of the optic fiber.
1. Previous Technique
In the treatment of certain cancerous lesions in human body cavities, such as the bronchii, the esophagus or the uterus, photodynamic therapy is being used with increasing frequency. This involves irradiation of the tumor using diffused light. This irradiation is conducted using appliances comprised of a catheter containing a fiber optic linked to a laser light source which can be introduced into the biopsy channel of a classic endoscope. In order to obtain light diffusion that is as homogeneous as possible and to prevent damage to the cavity walls, the tip of the catheter introduced into the cavity is surrounded by a balloon which, once it is in place, is inflated to support the cavity walls to be treated.
In the appliances currently used, in particular the one described in publication DE 39 09 843, when dealing with an irregular cavity, a layer of material with diffusing properties is applied to the cavity walls in order to obtain homogeneity in the light diffused. An elastic envelope can similarly be used. The vaporization of the diffusing layer is a delicate operation and, if an inflatable elastic envelope is used in this type of cavity, firstly the inflating pressure has to be sufficiently high for the envelope to press against the cavity wall which results in high and differentiated pressure constraints on the cavity walls and risks modifying tissue vascularization and, secondly, differences in thickness are created in the envelope wall which results in irregular light transmission.
2. Description of the Invention
The aim of the current invention is to eliminate these drawbacks by providing an appliance in which the elastic envelope, or small balloon, presses well against the surface to be treated and thus applies uniform pressure to the cavity walls, while the thickness of the balloon walls remain constant after inflation. In addition, the pressure needed for this inflation is weak, which means that the resultant pressure applied by the balloon on the cavity tissues to be treated is likewise weak and there is no risk of damage. In this way, there is a homogeneous back-scattering of the diffused light in all shapes of cavity to be treated while being careful with these cavity walls.
The appliance described at the beginning is characterized by the balloon which is fabricated using a mold shaped roughly like that of the cavity to be treated in order to take on its shape and to apply uniform pressure on the cavity walls.
Ideally, the balloon could be made by using a mold taken from the specific impression of the cavity to be treated.
In all its design versions, the balloon includes a neck designed to be slipped onto the tip of the catheter surrounding the diffusing section of the fiber optic and, as a result, the longitudinal axis of the fiber optic""s diffusing section is identical to the symmetrical axis of the balloon.
Preferably, the fiber optic is sheathed in a protective casing.
According to the preferred design type, the catheter includes, at the opposite extremity to that covered by the balloon, an axial aperture designed to receive the fiber optic and a radial aperture designed for the introduction of the means to inflate the balloon in the space bounded by the interior wall of the catheter and the protective casing sheathing the fiber optic.
The balloon can be inflated either with air or a sterile liquid, for example water.
In order to diffuse the means of inflation within the balloon, the tip of the catheter covered by the balloon has radial apertures, spaced at regular intervals and arranged around its periphery.
In all its design versions, the balloon is designed to be inflated after introduction into the cavity to be treated.
As an advantage, it can include the means to control the pressure applied by the balloon on the walls of the cavity to be treated.